Aircraft typically include a plurality of flight control surfaces that, when controllably positioned, guide the movement of the aircraft from one destination to another. The number and type of flight control surfaces included in an aircraft may vary, but typically include both primary flight control surfaces and secondary flight control surfaces. The primary flight control surfaces are those that are used to control aircraft movement in the pitch, yaw, and roll axes, and the secondary flight control surfaces are those that are used to influence the lift or drag (or both) of the aircraft. Although some aircraft may include additional control surfaces, the primary flight control surfaces typically include a pair of elevators, a rudder, and a pair of ailerons, and the secondary flight control surfaces typically include a plurality of flaps, slats, and spoilers.
The positions of the aircraft flight control surfaces are typically controlled using a flight control surface actuation system. The flight control surface actuation system, in response to position commands that originate from either the flight crew or an aircraft autopilot, moves the aircraft flight control surfaces to the commanded positions. In most instances, this movement is effected via actuators that are coupled to the flight control surfaces. Though unlikely, it is postulated that a flight control surface actuator could become inoperable. Thus, some flight control- surface actuation systems are implemented with a plurality of actuators coupled to a single flight control surface.
Although flight control surface actuation systems, such as the one generally described above, operate safely, reliably, and robustly, these systems can suffer certain drawbacks. For example, for some types of actuators, if the actuator is rendered inoperable, the remaining actuators that are coupled to the same flight control surface may not be able to move the flight control surface sufficiently to compensate for the inoperability. The inoperable actuator may therefore prevent, or at least inhibit, movement of the flight control surface. If the flight control surface is in a position other than in a neutral position during such an event, the aircraft may be difficult to handle.
Hence, there is a need for a system and method that will not prevent or inhibit an actuator from moving a flight control surface in the unlikely event that another actuator that is coupled to the same flight control surface becomes inoperable. The present invention addresses at least his need.